The present invention generally relates to high brightness light sources and more particularly to apparatus by which the outputs of multiple light sources can be beneficially coupled into a single output whose brightness is greater than that of the individual sources from which it is derived.
There are many uses for high brightness concentrated sources of light. Most of these applications require the use of a laser source, which are, to date, expensive and relatively complex. Therefore, laser sources are not applied to many problems needing a high brightness concentrated light source because they are too expensive and complex.
Light emitting diodes (LEDs) represent another possible source for achieving high brightness. However, a single LED or single array of LEDs operated continuously (CW) is limited in the brightness that can be obtained when imaged into a spot focus with a given numerical aperture as, for example, that of an optical fiber. In addition, the optical power out of an LED is limited because of the build up of high levels of damaging heat when operated CW near peak power levels. Nevertheless, LEDs represent an attractive alternative to lasers since they are less complex and expensive, are available over a range of colors ranging from the ultraviolet through the mid infrared spectrum, and can be modulated at decreased duty cycles to provide increased peak power without experiencing heat damage. Other sources of optical radiation that can be modulated to provide increased peak power by operation at decreased duty cycles include laser diodes, xenon flash lamps, and the like.
Hence, it is a primary object of the present invention to provide a low cost, high brightness concentrated source of light.
It is another object of this invention to provide a low cost, high brightness source that uses a multiplicity of relatively lower cost sources whose outputs are serially coupled as a single output whose brightness is higher than would otherwise be available from a single source.
It is another object of the invention to provide a low cost, high brightness source by serially coupling the outputs of a multiplicity of LEDs to provide a single source that is brighter than the brightness that otherwise could be made available from a single LED.
It is another object of the invention to provide a low cost, high brightness source by serially coupling the outputs of a multiplicity of LEDs of different color to provide a single source that is brighter and of different color than would otherwise be available from a single LED.
It is still another object of the present invention to provide a variety of different apparatus for serially coupling the outputs from a multiplicity of LEDs to provide a low cost, high brightness source.
Another object of this invention is to provide relatively compact and lightweight apparatus for serially coupling the outputs from a multiplicity of LEDs to provide a low cost, high brightness source.
Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter when the following description is read in connection with the drawings.